Turning an old PC into a thin client for Windows Remote Desktop

An office PC that is too slow for Windows 11, or a used thin client bought for little, makes a good Remote Desktop
client. OpenThinRDP turns it into a kiosk that starts straight into a sign-in form and opens the user's Windows
desktop in full screen. Nothing is installed on the Windows side and there is no licence per device.

• What the PC needs
• What it connects to
• Step by step
• Making it a good thin client
• When it is not the right choice

What the PC needs

Drivers are not a worry: the system is Debian 13 with its complete kernel and every firmware package
(hardware). The quickest test is to start it live from a stick: if the settings dialog shows an
address, the network works.

What it connects to

• A Windows PC with Remote Desktop on, e.g. the user's office PC (Windows Pro or Enterprise: Home cannot be a
  Remote Desktop host). Set its name as the broker.
• A Windows Server with Remote Desktop Services: session hosts or a VDI collection behind an RD Connection
  Broker. Set the broker and the collection.
• The same, in the cloud (Azure, AWS or any provider), through an RD Gateway or a VPN
  (desktops in the cloud).

Step by step

1. Download the ISO and write it to a USB stick
   with Rufus (DD mode), balenaEtcher or dd.
2. Start the PC from the stick. It is usually F12, F11, F9 or Esc at power on; enable USB boot in the firmware
   setup if the stick is not in the list. Turn off "fast boot" if the PC never shows the boot menu.
3. The live system starts by itself after 10 seconds. It runs from the stick and writes nothing to the disk.
4. In the settings dialog set the broker (or the name of the Windows PC) and the domain. Save, then sign in with
   a Windows account.
5. Happy with it? Restart from the stick and choose Install. It shows the disk it is going to erase and asks,
   then takes about three minutes. From then on the PC starts straight into the sign-in form, in a few seconds.

Making it a good thin client

• One place for all devices. Put the settings in a shared folder and use the manager, with
  updates for a few pilot devices first and a way back.
• Power. Set a schedule (POWER_ON_TIME, POWER_OFF_TIME, POWER_ON_DAYS), and set the device to switch off
  when the session ends (SHUTDOWN_SECS). Wake-on-LAN needs the firmware option on
  (configuration).
• The PIN. A PIN on the settings dialog (⚙) keeps users out of the settings.
• USB. Sticks appear in Windows as drives; signature keys and special devices are passed whole; webcams and
  headsets work in Teams.
• Company networks. 802.1X on the cable and WPA2/WPA3-Enterprise Wi-Fi are supported.

When it is not the right choice

• The user also needs local programs: a normal Linux desktop with a Remote Desktop client is better.
• Citrix or Omnissa Horizon: OpenThinRDP does RDP only.
• Azure Virtual Desktop or Windows 365: not supported yet.

Questions: FAQ. Compared with Linux Mint + Remmina and the thin client systems:
alternatives.